Kunz, R. M. (1971). The challenge of life. Switzerland: Basel and Stutgart.
Chicago Style aipamenaKunz, Robert M. The Challenge of Life. Switzerland: Basel and Stutgart, 1971.
MLA aipamenaKunz, Robert M. The Challenge of Life. Switzerland: Basel and Stutgart, 1971.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.